1. Field of the Invention
The present invention relates to phosphites, more particularly relates to alkyl aryl phosphites and thermoplastic compositions stabilized therewith.
2. Description of the Related Art
High ortho alkyl aryl phosphites and thermoplastic compositions stabilized therewith have been disclosed in Great Britain Patent 2039282. Generally, commercial tris nonyl phenyl phosphite (TNPP) compositions have had ortho levels of approximately 5 to 10 percent and para levels of between 90 and 95 percent. The Great Britain Patent 2039282 discloses TNPP compositions on Table 2 having ortho levels of 88 percent and para levels of 11 percent, and in Example 5 sets out TNPP having an ortho level of 88 percent. Page 1 of the reference on line 51 sets out the levels being at least 85 percent ortho. One problem with prior attempts to make unsubstituted para-ortho nonyl phenyl phosphites has been the difficulty in obtaining high purity para unsubstituted-ortho nonyl phenol. Due to the difficulty of obtaining such high purity material, prior attempts have utilized substituted para position ortho nonyl phenols in order to enhance the purity of the ortho position. Note that in the Great Britain Patent 2039282 that in reference to the examples 7 to 10 that it sets out a purity level of 93 percent to 99 percent as being achievable, but note that the only example involving a nonyl phenol has a methyl substituted para position. In other words, there historically has been difficulty in obtaining ultra high purity ortho nonyl phenol which has an unsubstituted para position, and as a result prior high ortho nonyl phenols utilizing an unsubstituted para position have typically been limited to purity levels of, for example, those set out in Table 2 and Example 5 being an 88 percent purity level. Prior ortho substitution levels of 80 to 90 percent have generally resulted in increases in hydrolytic stability of some 30 to 50 percent over commercial TNPP grades (5-10 percent ortho levels), and while such phosphites have exhibited enhanced levels of hydrolytic stability, there is still a need for higher degrees of hydrolytic stability due to the vulnerability of such phosphites to hydrolytic instability under humid conditions.